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I got my first Subaru legacy 93! Question of Cooling Fan On at cold weather


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12 replies to this topic

#1 ndu

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Posted 31 January 2005 - 07:25 PM

I got my first Subaru Legacy 93 last week. It is a AUTO and got 155000km on it and it was running very well.



I have been reading a lot of posts here before I bought the car. I have to say you guys helped me in making up my mind.



I have a question regarding the cooling fan. When I start the car, the temperature gauge is near zero. The fan is not on. After a while, the temperature gauge will reach the middle and stay stable. And the cooling fan (both fans) will be on. In cold weather like Toronto in the last few days (25 degree C below zero), the cooling fans are still on all of the time. I do not know if this is normal for Subaru Legacy 93 as a design feature. I am concerned if the fans are on all the time, they may be wear out soon. I have owned Toyota’s before and in winter, the cooling fan will not be on as often. The cold wind will cool the radiator sufficiently so that the fans do not need to be on. My Subaru certainly feels different in this aspect…..maybe other owners can let me know please?



Also, are Subaru cooling fans have different speeds as those in Toyota? I know in Toyota, there are high speed mode and low speed mode of fan operation…depending whether the A/C is on, the engine temperature etc. For example, if you turn on the A/C at low engine temperature, both fans will be on at low speed mode. When the engine reach certain temperature, both fans will be switched to high speed mode automatically. This transition is very noticeable……



By the way, the cooling system are “normal” in all other way: I got very good heat, the engine is not overheating, the temperature reading is always stable, and when enginine is cold, it reads zero.



Thanks in advance! I think I found a home for my car…..





#2 Beaudiggity

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Posted 31 January 2005 - 07:42 PM

I got my first Subaru Legacy 93 last week. It is a AUTO and got 155000km on it and it was running very well.



I have been reading a lot of posts here before I bought the car. I have to say you guys helped me in making up my mind.



I have a question regarding the cooling fan. When I start the car, the temperature gauge is near zero. The fan is not on. After a while, the temperature gauge will reach the middle and stay stable. And the cooling fan (both fans) will be on. In cold weather like Toronto in the last few days (25 degree C below zero), the cooling fans are still on all of the time. I do not know if this is normal for Subaru Legacy 93 as a design feature. I am concerned if the fans are on all the time, they may be wear out soon. I have owned Toyota’s before and in winter, the cooling fan will not be on as often. The cold wind will cool the radiator sufficiently so that the fans do not need to be on. My Subaru certainly feels different in this aspect…..maybe other owners can let me know please?



Also, are Subaru cooling fans have different speeds as those in Toyota? I know in Toyota, there are high speed mode and low speed mode of fan operation…depending whether the A/C is on, the engine temperature etc. For example, if you turn on the A/C at low engine temperature, both fans will be on at low speed mode. When the engine reach certain temperature, both fans will be switched to high speed mode automatically. This transition is very noticeable……



By the way, the cooling system are “normal” in all other way: I got very good heat, the engine is not overheating, the temperature reading is always stable, and when enginine is cold, it reads zero.



Thanks in advance! I think I found a home for my car…..




The cooling fans always come on at a certain temp. Usually at 210 or somewhere around there. Your saying they come on at the normal time and your car is putting out good heat and it doesn't overheat. I'd just leave it and it should be fine. If your still concerned just take it to an import mechanic and have them test the relays on your fans.

#3 Legacy777

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Posted 31 January 2005 - 09:01 PM

The fans should cycle on and off, however the fans will stay on all the time if the hvac selector is on either of the A/C selections or on the defrost setting.

#4 ndu

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Posted 31 January 2005 - 09:53 PM

This is my problem: I do not think my fan cycles on and off as I expected.....as to A/C selections or on the defrost setting, I noticed this because even at low temperature, the fans will be on as soon as they are selected, so I made sure they were off, and I still not seeing cycling on and off of my fan.

Any suggestions?

The fans should cycle on and off, however the fans will stay on all the time if the hvac selector is on either of the A/C selections or on the defrost setting.



#5 Legacy777

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Posted 01 February 2005 - 08:43 AM

Your coolant temp sensor might not be functioning properly...or possibly the thermostat.

One other thing might be the concentration of antifreeze & water mix you have in there. If it's more then 50/50, the system may not be transferring as much heat as it needs to, and the fans are staying on.

#6 Skip

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Posted 01 February 2005 - 09:00 AM

Fans are single speed - on or off

I'm with Josh on the FI coolant temp sensor (CTS)

By chance have you seen the check engine light flash on occation?

When my CTS went bad my fans would run constantly after
the engine had been running a certain period. (94 Leg 194kmi)

You might want to check the connections first.

These are relatively cheap sensors about 30 GWs

Located on the ldriver's side rear portion of the intake manifold (American model)
just behind the PVC
connection to the crankcase.
Screws in horizontaly, will be brass in color.
Mine has a brown plastic connector.

Hope this helps.

#7 ndu

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Posted 01 February 2005 - 11:48 AM

Thanks Legacy777 and Skip for your advice





By chance have you seen the check engine light flash on occasion?”



No, my engine light did not come on.



Skip, I have a question about CTS: is it a analog type sensor or it is an “digital” sensor with on and off ? (like in Toyota, the cooling fan is controlled by a “on” and “off” cooling temperature sensor. Also, is this sensor only used for cooling fan or it is also used for other things?



Thanks guys, you are great!

#8 Skip

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Posted 01 February 2005 - 11:59 AM

CTS is an analog variable resistance thermosensor.

the ECU will turn on the fans (one speed, only speed) when
it see a problem with the CTS reading
(out of the normal parameters)

This is done in case the engine is overheating.

With a faulty input it fails safe.

#9 ndu

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Posted 01 February 2005 - 09:32 PM

Skip, thanks for your answers.

In your previous reply, you said:

"Located on the ldriver's side rear portion of the intake manifold (American model)
just behind the PVC
connection to the crankcase.
Screws in horizontaly, will be brass in color.
Mine has a brown plastic connector."

Are you sure it is on the driver's side? I think my car (1993 Legacy) it should be on the passenger side. I saw two sensors side by side on the passenger side of the engine, on top of the coolant tube. One fits your description "brass in color. with a brown plastic connector." It has two wires coming out of it. I think this must be it. The other one is much smaller in size and has only one wire coming out of it. I think this is for the temp gauge. what do you think?

Thanks again.

#10 ndu

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Posted 02 February 2005 - 03:28 PM

May be there is nothing wrong with my cooling fan after all!



I have been reading the shop manuals you guys posted here and I noticed in "1992_Subaru_Service_Manual-Engine_&_Wiring" Section 2-7, 8 "Radiator Fan Control", the radiator fan is controlled by a) Water Temperature Sensor B) Vehicle Speed Sensor #2 and c) A/C Switch. Since every time I checked the fan, the car is always stationary (I do not know how else to check!) that is why the fan is always on (after the engine is hot). Maybe as soon as the car starts moving (or reach certain speed), the fan will stop? This is a much more sophisticated design than I previously thought. The question is, how do I verify this feature? (Funny thing is, I am in a business where verification and validation of design features are my daily concerns, I guess old habit is difficult to get rid of....Hahaha....)

Oh, Skip, according to the same book, not only those 3 signals can turn "on" and "off" the fans, they can also set the fans in "HI" or "LO" speed. Looking at the schematic, there are two control lines (other than the grounf wire) for each fan, I studies them in some detail and maybe the fan can operate in HI or LO mode. Again, this is a feature that is not easy to verify.


What you guys think?


Since everything else looks OK, I am not going to worry about it now other than keep a close eye on it.



I learned a lot from you guys.



#11 Spazz698

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Posted 02 February 2005 - 05:48 PM

May be there is nothing wrong with my cooling fan after all!



I have been reading the shop manuals you guys posted here and I noticed in "1992_Subaru_Service_Manual-Engine_&_Wiring" Section 2-7, 8 "Radiator Fan Control", the radiator fan is controlled by a) Water Temperature Sensor B) Vehicle Speed Sensor #2 and c) A/C Switch. Since every time I checked the fan, the car is always stationary (I do not know how else to check!) that is why the fan is always on (after the engine is hot). Maybe as soon as the car starts moving (or reach certain speed), the fan will stop?


I have the same car, the fans should still turn on and off periodically when parked. when the car's warm the fans turn on and off every 4 minutes or so (guessing)I dont know if your's will do this but when the fans on my car turn on and off you can hear a very quiet click. I only hear this when the radio's not on and my rpms are steady.

#12 Skip

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Posted 02 February 2005 - 06:03 PM

ndu, you are correct, my old brain failed again

the sensor is on the pass side

as for the hi/lo feature

I believe you and will look in my FSM

Why not run a small speaker wire
into the cockpit from the two hot control leads you speak of

Wire it to two 12v lamps or LED's
gound the other side of them in the car

you could watch the fans for a while

I think I will just for info on their operation

#13 Tiny Clark

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Posted 03 February 2005 - 03:18 AM

If you really need to know, tap into the fan wires and hook a bulb them. Run the wires under the back of the hood and leave the bulb clamped down by a one of your wiper arms so you can see it while driving. If the bulb is on, the fan is on.

Tiny
P.S. Are you from Missouri?




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